Running rich

[dgdara]

Hello guys, I have a 1999 535i, swapped with a M62B44 from X5, everything done correctly, I was having the same issue on the old engine - running rich, here are the fault codes I get all the time + from time to time camshaft position sensor bank 1, also I cannot tell, but I think the car is not as fast as it should be.

[dovlet]

Check front oxygen sensors. MAF sensors. Is your engine m62b44tu or non tu?

[dgdara]

It is M62b44TU, front oxygen sensor on bank 1 was dead (the heater) and replaced, the other one is old, but no fault code given, so haven't replaced, new MAF, since the MAF from 3.5 is not compatible with the 4.4 engine.

[dovlet]

Ok, for me it looks like next:
1. If your oxygen sensors works your ECU should have correct it just give a time.
2. How do you know that engine works reach? AFR sensor & gauge installed?

If you waited enogh and afr is showing still reach then try to check injectors, perhaps some of them left open. Also, it could be due to retarded ignition timing. What is your ECU setup? Is that for m62b44tu?

Also, MAF for m62b44tu and m62b35tu is the same. The only body crocc section area is different.

[dgdara]

I'm considering this because my car often pops when I let go of the gas pedal, or stays at 1k rpm and just throws out fuel, plus it smells like unburnt fuel in the bank

[MIKYZZ4]

Check fuel pressure, also check for intake leaks caused by cracks at rubber intake boots, associated vacuum hoses.
If you were in the States I would recommend a professional smoke test.

[geargrinder]

Yep. Just follow the logic... Running rich means either too little air, or too much fuel, or a measurement problem.

MAF and O2's are measurement problems. If the MAF is brand new but an 'off brand' (ie cheap copy) you might be suspicious of it. You have same problem on both banks, so, for me O2 would be less of a suspect. (by the way posting up the actual fuel trims would be helpful to see if they are truly about the same across the banks... be careful if you clear codes/adaptations you'll reset them then we won't know what the trims are).

Actual air constriction is unlikely.

Too much fuel is more possible. Its' across the banks so its not just one or two leaky / failed injectors. As Miky says, check that fuel pressure... if the regulator is bad then you can have that issue. I believe sometimes if the supply/return lines are accidentally switched at the regulator, you can get crazy high fuel pressures. That's the kind of mistake that's often made during fuel filter/regulator changes. A failed tank-vent system can also cause super rich running but its usually only under certain conditions - specifically when the tank is super full and the vent sucks fuel through. Doesn't seem the case here.

[dgdara]

MAF is brand new, oem, one of the o2 sensors is replaced and the other one is still the old one. There was indeed an issue with the intake, I've taken care of it, fuel trims seem to look okay, I'm posting a video for you to check it out as well. Cats are out, there are no cats in the exhaust (the way I got the car).

[geargrinder]

No trims? Ok either you reset adaptations or the codes shown above are shadow and "not currently present". If the latter then maybe you have no problem.

[dgdara]

I've reset the trims couple of times, codes come up every time, also when I let go of the gas I hear the exhaust "rumbling" and "popping".

[geargrinder]

I guess I wasn't clear enuff.

Theres no way you're getting those codes and having "OK" trims. You are either not looking in right places or misinterpreting numbers.

- - - Updated - - -

Btw the backfires classic symptoms of running too rich. Kinda "good" in the sense it backs up the general consistency of diagnosing

[TheAngryBear]

Over on the other channel this discussion is occurring as well. Turns out the cats have been removed but the O2s are operational. Might have something to do with cat efficiency...


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[dgdara]

I've reset the trims couple of times, codes come up every time, also when I let go of the gas I hear the exhaust "rumbling" and "popping".